For 1990-2009 cars only
Circuit Description
The PCM uses the ECT sensor to monitor the engine for an over temperature condition. This condition occurs when the coolant temperature is above 131°C (268°F). When an over temperature condition is present, DTC P1258 will set. The PCM will disable two groups of four cylinders by turning OFF the fuel injectors. By switching between the two groups of cylinders, the PCM is able to reduce the temperature of the coolant.
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
| • | The PCM detects an engine over temperature condition. |
| • | The above condition is present for at least 8 seconds. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator Lamp (MIL) during the first trip in which the diagnostic test has been run and failed. |
| • | The PCM will signal the IPC to turn ON the Service Engine Cooling System Message. |
| • | The PCM will alternately disable2 groups of 4cylinders by turning OFF the fuel injectors. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame and File Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL OFF after three consecutive trips that the diagnostic has been run and passed. |
| • | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using the scan tool Clear DTC Information function. |
Step | Action | Yes | No |
|---|---|---|---|
1 | Was the Diagnostic System Check for Engine Cooling performed? | Go to Step 2 | |
2 | Check the engine cooling fans for proper operation. Are the engine cooling fans operative? | Go to Engine Overheating |
